I've always dreamed of leaving my house spontaneously and call back to anyone listening "I'm going out" without any hassle. But frankly, that isn't possible when living with typical Asian parents. As far as I'm concerned there are 3 main reason why these parents say NO.
1) You will be classed as a "loafer" by society.
This is neither referring to a type of shoe nor a "loaf er bread". This is someone who looks as if they have no purpose to their life and has nothing better to do than walk around aimlessly when they should doing some kind of work.
2) You have already been out once in the past month.
You have to tell your un-Asian friend, "I'm sorry I can't meet you in our hometown for a couple of hours today as I have already been to Marks&Spencer with my mum last week to return something."
3) There is no reason.
There's no responsibilites at home, you've got suitable transport to get there and back, there won't be anyone of the opposite sex there, you'll be home before it gets dark. But "NO, because I said so."